Apple Xcode is a macOS IDE used for developing iOS and macOS apps. It is available for free from the Mac App Store and is required to publish iOS apps to the iTunes App Store and macOS apps to the Mac App Store. The software provides a suite of tools to help developers build user interface components and write source code.

Xcode includes all the tools needed to build and publish apps from start to finish. Xcode's Interface Builder provides a design canvas to create user interface components, as well as to set properties for interacting with your source code. The Interface Builder can also easily switch from light to dark mode for developing dark macOS apps (introduced in macOS Mojave). The program integrates with popular version control tools such as GitHub, GitLab, and Bitbucket and also provides its own local revision tracking system called snapshots, allowing developers to track revisions of source code.

The IDE features an impressive source code editor that makes it easy to visualize and select sections of code and comes with a built-in refactoring and transformation engine. Changes you make to your code are highlighted next to each line and you are instantly notified if you have created a conflict. This is especially helpful when working collaboratively with local changes and commits from team members upstream in the source repository.

Debugging and performance tools allow developers to test for memory leaks and examine app efficiency during runtime. These tools can be customized or you can use templates included with Xcode to build using the same tools as Apple. Also, Xcode comes with Simulator, a tool that allows you to prototype and test builds of your app by simulating iOS, watchOS, and tvOS devices.

Xcode is a great tool for developing apps and has come a long way since the first version of the software. Apple has streamlined many features and continues to make development easier for app developers. Keep in mind that, while you can develop with Xcode for free, you must subscribe to the iOS and Mac developer programs before you can distribute apps on Apple's stores.